


julian santiago and the case of the sister's mystery boyfriend

by amyscascadingtabs



Category: Brooklyn Nine-Nine (TV)
Genre: B99 Summer 2019 Fic Exchange, Character Study, Developing Relationship, F/M, Family, Fluff, Humor, Original Character(s), Pre-Relationship, Prompt Fill
Language: English
Status: Completed
Published: 2019-08-03
Updated: 2019-08-03
Packaged: 2020-07-30 13:50:02
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,522
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20098222
Author URL: https://archiveofourown.org/users/amyscascadingtabs/pseuds/amyscascadingtabs
Summary: Eventually, he makes the educated guess that there must be someone else in her life. She must have wanted for this to break-up to happen, he figures, and a new mystery lover could very well be the reason. Julian simply has to figure out who it is.written for the b99 summer 2019 fic exchange, following the prompts 'amy's brother finding out she's dating someone from an instagram post' and 'peraltiago from a third party's perspective'.





	julian santiago and the case of the sister's mystery boyfriend

**Author's Note:**

  * For [Alys0](https://archiveofourown.org/users/Alys0/gifts).

> hi! hi! i made it! with one day to go before the deadline!!
> 
> i had very fun coming up with the concept of this fic. it ended up being a lot more brief than i suppose it could have been because i needed to finish it on time and my motivation hasn't been the best with everything currently going on in my life, but i hope you can enjoy it anyway! thank you so much for the creative prompts aly <3
> 
> disclaimer: this is a work of fiction, and my view and portrayal of the cops in b99 is not an accurate representation of how i feel about the actual nypd and police. it is not meant and has never been meant to be viewed as such, and it is my deepest wish that you do not use these characters and these portrayals as a way to affect your feelings about police in real life. thank you.

**DECEMBER 2014**

Julian Santiago considers himself to be pretty close with his only sister. He's only two years older, they've gotten along throughout most of their childhood, and still do today. They're piano portrait buddies, although he accepted a while ago that he’ll always be a little bit closer to the stairs than she is. They shared a room as well as secrets growing up, and she's the first person he tells when he meets his first real boyfriend. Likewise, Julian is the first Santiago brother to learn when Amy gets together with Sergeant Teddy Wells and the first to learn when they break up. They're close, and out of all the seven competitive brothers, Julian likes to think he's the one who knows and understands his sister best.

It's a mystery on multiple levels when he can't figure out how  _ okay  _ she seems about the breakup. His sister, the person who cried for days straight when she broke up with her college boyfriend, his sister who has never been known for taking relationships lightly or being far from tears when she’s going through something, is sitting in their parents’ couch a mere five days after her breakup and seeming fine. She’s laughing and grinning in the most genuine way he recognizes, nodding with surprise when he asks if she’s okay, and Julian understands if she wants to appear strong in front of their hyper-judgmental parents, but this is eerie. She’s  _ too _ okay. It’s mind-boggling, and either he’s not getting an answer or he’s not asking the right questions, but eventually, he makes the educated guess that there must be someone else in her life. She must have wanted for this to break-up to happen, he figures, and a new mystery lover could very well be the reason. Julian simply has to figure out who it is. 

It doesn’t take him many hours - two, actually - before he has a guess. He’s heard his sister talk about her detective partner, Jake Peralta, before, but this is excessive. It starts with a retelling of some funny anecdote he’s told once, continues with her mentioning how she won over him in a confusing set of games and ends with further repetitions of  _ Jake said this _ and  _ Jake told me that _ until Julian is as certain as can be. They're dating, he knows it, but he has to be sure - he has to find some way to dig this secret out of her and be the first of the brothers to know - so he brings it up.

Not in front of everyone, of course. He’s made that mistake before and it ended with Amy being too furious to speak to him for  _ weeks _ . No, he waits until his dad suggests the siblings go out on a walk while Camila finishes up what is sure to be a delicious roast dinner, and while he’s not by definition alone with his sister, it’s the maximal amount of primacy which can be had during Santiago family gatherings. David and Victor are power-walking fifty feet ahead of anyone else, Luis and his wife Emma are walking thirty feet behind with their three-year-old twins. Tony, Isaac, and Christian are close but too deep in conversation about different kinds of protein powder to listen to anything else, their respective girlfriends are deep in conversation about what Julian thinks is a reality show but might as well be politics, and Simon is trying to keep up with David and Victor while holding a camera in front of his face. It’s chaos, but Julian finally has a chance to have a conversation only with Amy, so he jumps on it. 

“So, that Jake guy, huh?”

“What?” Amy flinches, looking at him like he just started speaking Russian to her. “Why are you bringing him up?”

“You two are definitely dating, huh?”

“ _ What _ ?” She nearly screams this, earning herself a confused glance from everyone nearby, and Julian almost jumps to the side in shock. “What - why are you - what would make you think that?”

“I don’t know”, he shrugs, “maybe because you’re mentioning him once every five minutes?”

“He’s my  _ work partner _ .”

“Who you talk about constantly.”

“I don’t talk about him constantly!” Amy’s still gaping, nose scrunched and eyes clearly judging him for his apparent stupidity. “That’s - you’re - I don’t.”

“You do, though.”

“I don’t!”

“Sure”, Julian grins. “I know you just want to keep it a secret from mom and dad, that’s fine, but you can tell me.”

“Jake and I aren’t dating!” She’s wheezing her words, looking anxiously around her before lowering her voice further. “We’re not. We’re really not.”

“But you’re… something?”

“He has a girlfriend, Julian.”

“Ohh…” He contemplates this confession, the cogwheels in his brain working and immediately jumping to the next guess. 

Except she wouldn’t. His sister wouldn’t. Or would she?

“Are you, uh -”, he whispers, “ _ are you the other woman? _ ”

“ _ JULIAN! _ ” They’re earning themselves looks and raised eyebrows again, now also from an older lady walking past them. Amy shoots her an apologetic smile before returning to the conversation. “Trust me, I’m not in love with Jake. And even if I like him - it wouldn’t matter.”

“Why wouldn’t it matter?”

“Because I would never date someone I work with, dumbass! It’s unprofessional.”

“You dated that pilsner guy -”

“Teddy and I worked at different precincts. Jake and I work at the same. It would be...” She grimaces. “I don’t know. I just don’t think it would work. Either way, it doesn’t matter because I don’t like him.”

“You’re talking about him a lot, is all I’m saying.”

“ _ Julian _ ”, she says his name like it’s a warning about life and death. “Let. It. Go.”

“Like the Frozen song?”

“You’re hopeless”, Amy declares, walking away from him in a pace so rushed he has to jog to keep up with her. 

“Fine! Fine! You don’t like Jake!”

It pains him as an older brother to give his sister that much privacy when he could be repeatedly teasing her, but Amy’s threatened to beat him up once before and Julian knows from experience his sister is  _ strong. _ As tempting as it is to do the opposite, he lets it go. 

  
  
  


**OCTOBER 2015**

Julian doesn’t ask his sister more questions about her love life for the year that passes by. Jake the work partner must still be dating someone else, seeing how Amy steers clear of him bringing up for the next months. Whether she has feelings for the guy or not, Julian’s still unsure, but asking seems to do no good and eventually, he gives up.

He can’t shake the suspicion that she’s dating someone else, though. Every time they meet up that summer, Amy is in a better mood than ever. She’s practically glowing every time someone asks her how she’s been, laughing and participating in every conversation even when she says she’s tired from work, and there seems to be an air of confidence and  _ happiness _ around her that he’s not seen since his sister was promoted to Detective. Whatever - or whoever - is causing it, Julian can’t help but be happy for her. She still mentions Jake now and then, but nowhere near the frequency she once did; whatever unrequited crush was once there, he figures it must have calmed down. 

In the end, Julian doesn’t give much thought to the possible mystery boyfriend. If it was serious, Amy would surely tell them, or at least tell  _ him _ . Therefore, it comes as a pure shock when a late October evening, his half-hearted Instagram scrolling leads to a major discovery. 

Julian recently moved in with his boyfriend of five months - Lucas - and while he usually doesn’t have as much time to spend on social media as he’d like, he’s found that during an episode of  _ Game of Thrones _ is his best shot. Lucas is too into the show to care what Julian does as long as he can rest his head on Julian’s shoulder and have his hair played with, and the episodes are long enough for Julian to thoroughly go through his own Twitter, Facebook, and Instagram feeds. So thoroughly, in fact, that sometimes he has time to go down the rabbit hole of random accounts and comments discussing Broadway shows or veganism, or simply do some benevolent stalking of his loved ones. Go through what accounts his sister follows, for example, and see if there’s anything juicy there she’s not telling him during their weekly phone calls. 

There are a lot of inspirational accounts about books and studying, even an account that seems to be centered specifically around laminated documents. She dutifully follows  _ simon_says-  _ the Instagram created by their youngest brother to advertise the supposedly successful YouTube channel no family member truly understands the point of - as well as a bunch of her friends from college and what seems to be every single Santiago family member who has social media. She follows a single account for a handmade jewelry store that Julian quickly scrolls through, and then she follows her co-workers.

Jake Peralta’s Instagram is frequently updated. Mostly with quirky selfies of himself, but also with pictures of chicken wings, Taylor Swift records, and pictures taken together with a short-grown man in beige clothing tagged as  _ charles-foodie-boyle _ . He’s posted a single selfie in which Amy appears as well, grimacing behind her desk, but Julian doesn’t make anything of it. Considering there’s a twenty-to-one ratio of pictures Charles is tagged in versus pictures Amy is tagged in, he would almost consider it more likely that Jake’s dating  _ him _ . He checks out Charles Instagram, simply out of curiosity. That’s when the heart attack occurs.

Charles Boyle posted a picture merely an hour ago. It’s taken in a gruff-looking bar, the lighting a little dim and the details a little out of focus, but he can see the three people in it clear as day. Charles is in the front of the picture, smiling enthusiastically and doing a thumbs up, but Julian’s attention is drawn to what’s happening in the background. His sister, wearing a purple blouse he’s seen at many a family dinners and her hair up, is pictured  _ kissing _ the one and only Jake Peralta.

Julian has never been so angry about an application lacking a zoom function before. Not that he needs it; it’s clearly his sister and it’s clearly Jake Peralta, he’s looked at the man’s face in enough selfies to be certain, and they’re clearly kissing. She even has a hand on his shoulder, displaying more PDA than Julian had ever thought his sister was physically capable of. There are two beers next to them on the bar table, but it’s a work night and Amy’s not the type to get black-out drunk on weeknights. Not black-out drunk enough to be kissing random people. No, Julian has to get the bottom of this, and he has to get to the bottom of this  _ now _ . 

“Lucas?”

“Yeah?” His boyfriend’s voice is distant, his green eyes focused on their television screen.

“I have to make a phone call. Family emergency.”

“Okay,” Lucas mumbles, squeezing Julian’s knee when he disentangles himself and leaves for their bedroom. “Be back soon?”

“I promise!” He half-shouts, unsure if he’ll be able to stick to the wording of  _ soon _ . He has a lot of questions for the person he’s about to call, and he’s still formulating most of them in his head as his phone searches for and calls up Amy Santiago.

She answers after three signals. She must still be at the bar, he judges from the odd clinking glass and the muffled conversations in the background, and there’s a confused tone to her voice when she speaks.

“Julian? Did anything happen? Is there an emergency of some kind?”

_ You bet there’s an emergency _ , he wants to say.  _ You not telling us about your dating life _ . 

“You’re dating Jake Peralta, aren’t you?”

There’s silence on the other end of the phone. Then, a yet more confused, but also curious, voice.

“How on Earth did you figure that out?”

“I, uh, Instagram-stalked you,” he admits, somewhat sheepishly. “I was bored, and I.. I went onto Charles Boyle’s account? He had a picture of you and Jake, that he posted like an hour ago. You two were… kissing.”

Yet more silence, then a loud and angry statement, shouted at someone else on the other side. 

(“Charles! I’m going to kill you!”

“Ames, why are you killing Charles  _ this  _ time?”)

“Sorry,” she says when she returns to the phone, not with as much background noise now; she must have walked a bit away. “I’ll yell at him later. But yeah - uh - it’s true, I guess.”

“So you’re dating?”

Amy sighs. “Please don’t tell mom about it. You know how she is about everyone I date.”

“Yeah, yeah, you don’t have to remind me twice,” he assures her, “but now tell me everything. How long have you been dating?”

“A little over four months,” she admits. “I mean, I almost thought it was obvious - I feel like I’ve talked about him a lot.”

“You talked even more about him before you were dating!”

“Did I?”

“Yes.”

“Really?”

“ _ Yes _ . You literally didn’t shut up about him,” Julian snorts, thinking back to when he first questioned her about it on that winter walk. “Either way - I’m… happy for you.”

He can’t see her reaction on the other end of the call, but he has a distinct feeling that she’s smiling, the kind of shy but genuine smile often accompanied by blushing cheeks.

“Thanks, Julian. I’m really happy, too.”

“He’s treating you well and all those things, right?”

“Obviously.”

“Because I’d beat him up otherwise. Or I’d send Tony to do it,” he offers. “Or pay Simon to make a video about him? Point is I’d find a way.”

This makes Amy laugh, a burst of melodic laughter that reminds him of inside jokes and morning cartoons when they were younger.

“I think I’m good, thanks. Jake’s amazing. I can tell you about him over lunch next week?”

“Lunch next week sounds great.”

“Talk to you later?”

“Absolutely. Have a good night, Ames.”

She hangs up on him. After making a single victory gesture in the bedroom mirror, Julian immediately phones Tony to inform him there’s a winner in the bet on whether Amy would ever date a coworker.

  
  


**JANUARY 2016**

  
  


Julian meets the famous Jake Peralta for the first time four months later. At that point, he's built up so much curiosity it feels like he's bursting at the seams, itching to actually meet the person he's heard about since the day his sister transferred to the Nine-Nine. He's excited, but he’s also wary. Amy's talked about this guy in every single phone call and meeting he's had with her for the last months, insisting that  _ you’d love him, Julian, I really think you’d get along _ until Julian had started to question whether she was trying to pair  _ him _ together with Jake. 

The information Julian has gathered is that Jake is supposedly brilliantly funny with a sweet personality, an amazing detective, worthless at math and basketball and an intense fan of Die Hard and Taylor Swift. (The last piece of information, Julian’s gathered on his own through more professional brotherly Instagram stalking. It’s the same method he’s used to discover that Amy doesn’t, for once, have horrible taste; Jake Peralta actually  _ is _ cute when he’s not grimacing in pictures. Not Julian’s type, but cute.)

It’s overwhelmingly positive information. Then again, Amy described Teddy Wells with nearly as many positive adjectives to a beginning, and the hours Julian spent listening to that man talk about pilsners are hours he’ll never get back. Therefore, it’s a positive surprise when Jake shows up to the casual siblings-and-partners dinner and lives up to Amy’s description.

He’s far more handsome in person than his Instagram feed makes him out to be, which Lucas seconds before mentioning to Julian that someone should give Jake a proper lesson in taking non-quirky selfies.  _ As a service to the world _ , he says, and Julian punches him in the shoulder before agreeing.

Jake is visibly nervous to meet so many of the brothers at the same time, seeming tense and giving short replies to a beginning, but once he relaxes, Julian is fully prepared to agree with his sister - Jake  _ is _ funny. He’s genuine, a natural in conversations, and he chimes in with the jokes or comments no one else would think of. He’s effortlessly nice, almost remembers every different brother’s name, and it’s clear that he meets the most obligatory criteria; he makes Amy happier than Julian’s seen her in a long time. She’s almost shining, grinning and laughing and watching her boyfriend with a gaze so enamored it would have made Julian nauseous if it had been anyone else. He later catches Jake looking at her in the exact same way.

The new couple sticks together for the duration of the evening, never leaving each other’s side for more than a couple minutes. It doesn’t even seem like they’re thinking of it but simply gravitate towards each other without a second thought, seeming displaced once the other one leaves. Julian watches them share secret smiles, looks and squeezes of hands without having a clue what the two of them are communicating, only that they seem to be checking in with each other, speaking a sort of private language. It’s all kinds of cheesy and it’s all the lovey-dovey-ness he can stomach for a day when he can see them kiss through the window the moment they’ve left, but he loves his sister, so he lets her be. He’s happy for her.

  
  


**NOVEMBER 2017**

  
  


Because Julian now follows Charles Boyle on Instagram, he finds out about the engagement through an excessive number of insta-stories the moment he wakes up on November 1st, 2017. Amy doesn’t answer her phone for a full three hours after Julian’s first tried to reach her (he does  _ not _ want to know why), but when she does, she facetimes him on his lunch break to show off the ring and tell the slightly insane story of how the proposal went down. 

The proposal follows almost immediately upon Jake’s release from prison. Even before that, the couple had already spent six months apart while he was in witness protection and Amy told all her brothers they were broken up but whispered the truth into Julian’s ear late at night after a couple of glasses of wine. From the stories Amy’s told him, he’s wondered more than once how many more brutal hurdles this couple will have to face, and it’s with great happiness he congratulates her on the engagement. She deserves this. Jake deserves this,  _ they  _ deserve this, and he couldn’t be happier for them.

“So I win the craziest engagement for the year,” Amy brags when she’s told him everything, and Julian has to agree that she does. Then he starts sketching up plans for a private two-person heist he can surprise Lucas with. 

  
  
  


**MAY 2018**

  
  


Julian isn’t at his sister’s wedding. He was going to be, thank you very much, he wasn’t  _ intending  _ to miss it, but apparently, nothing’s ever simple in his sister’s life and a bomb threat interrupts the planned event and sends every member of the Santiago family back to their respective homes and hotel rooms. The actual wedding, he learns, takes place outside their precinct with the couple’s colleagues and a few gawking New Yorkers as witnesses, while the real family has to be happy with an impromptu dinner at a nearby restaurant the next day. 

It's a chaotic dinner. Luis, Christian’s and Isaac’s kids are spilling food and getting overtired, Roger Peralta and Victor are massaging their own shoulders while shooting each other threatening looks, Simon’s filming and there is definitely a hint of competition to every toast held by the bride and groom’s parents. Still, it's pleasant, and there is laughter and smiles all around when the just-married couple tells the story of how their wedding day went down. 

They're almost sickeningly in love, Julian notes, acting like they're part of their own private universe where they can finish each other's sentences and give each other glances that he supposes are meant to be secretive but definitely isn't. They were only a couple of minutes early to the dinner - late in Santiago measurements - and the buttons on Jake’s shirt were clearly buttoned in a haste. Julian loves his little sister and all, but he did  _ not _ need to think about that image of her.

In the end, he's happy if she's happy, and just-married Amy is by far the happiest Amy he's seen in his life. She barely listens when he tells her he and Lucas are leaving, watching Jake with googly heart-eyes as he's telling Tony some story and glancing back at Amy about every tenth second. 

It's what she deserves. As much as he doubts any man could ever be good enough for her, the way Jake watches Amy with awe every time she speaks is everything Julian could ever wish for his sister.

**Author's Note:**

> simon santiago the influencer is an icon i came up with together with siân and i need to write more about him. he does a lot of collabs with zoella. don't ask questions.
> 
> also yes, julian has a boyfriend, because i'm bi and i say so. there are so many santiago brothers there's no way they're all straight. 
> 
> i hope you enjoyed some of the jokes i tried to put in this. also, no, instagram didn't have zoom in 2015!! i checked their wikipedia!!!
> 
> thank you so much for reading and feel free to check out more of my stuff! and let me know if you want julian (or any other brother) to return!


End file.
